This problem has now been solved! After four weeks of reading other posts and stewing on why it kept happening, I stumbled upon the answer.
It lies in the bios setup. After reading a post on a model that was not related to mine at all, I decided to use the same answer to see if it applied.
I went into my bios setup and sure enough, there was an option to switch on or off the brightness of the lcd to save power while running on battery.
I switched this off, but only after a few more restarts with the power being completely shut down did I realize the issue has been resolved!
Thank you very much for the suggestions from Andy posted earlier.
Happy New Year to all across this great user forum!